Telemetering



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ATTORNEYS COUNTING CHAIN RELAYS 14 Smets-sheet 3 INVENTOR.

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F IGIO INVENTOR. LEMUEL FK. BREESE ATTOR NEYS April 9, 1957 L. R. BREESE 2,788,515

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i i308' T INVENTOR. LEMUEL R. BREESE nited States Patent 'rnLnMErnniNG Lemuel R. liti-cese, Galion, Ohio, assigner to North Electric Company, a corporation of @itin Application September 1, 1950, Serial No. 182,671

2i Ciaims. (Cl. 340-180) The present invention relates in general to automatic signalling equipment which is adapted for control of a series of remotely disposed operating units, and is particularly concerned with the provision of new and novel information transmitting means for use with remote control systems of this general type.

As a result of the extensive demands of industry which are made of the various types of power systems today, the systems have become increasingly complex in structure and are invariably dispersed over large geographical areas. The individual maintenance and supervision of the various units of the system which are located at points distantly removed from each other is, of course, an eX- pensive operation, and there has accordingly been a definite trend toward the centralization of control of the individual components of power systems at a single or control master station. Several specific examples of remote control applications in the field include the control of circuit breaker equipment for power lines, flood gates on dam installations, transformer switching and distribution stations, automatic substations such as used in railroading and mining fields, automatic electrified pumpin stations, and substation generating installations.

Along with the trend toward centralized control, there has arisen an increasing demand for improved types of supervisory remote control equipment, and such demand has been particularly well met by the novel control system which has been set forth in a copending application which was led by L. R. Breese et al., on April 4, 1950, which received Serial No. 153,962, now Patent No. 2,616,959, issued November 4, 1952, and which was assigned to the assignee of this invention. The present invention is directed to one of the features of that disclosure, and particularly to apparatus for providing indications at the control station of the condition of the controlled members at the distantly located stations.

The installation described in the copending application includes a dispatch or control station which is arranged to control the operation of a plurality of circuit breakers (100 in number) disposed at a distantly located substation, such selective controlling operation being accomplished over a single communication channel which extends between the several stations. The control station is arranged to transmit certain signals or orders to the chosen substation and the substation is arranged to perform these orders and verify their execution. The equipment as disclosed therein effects four basic operations in each given controlling operation of a circuit breaker, that 1s (a) The selection by the operator of the circuit breaker unit to be controlled,

(b) The transmission back by the substation of auto matic check signals to provide proof of correct selection,

(c) The operation of the selected circuit breaker,

(d) The automatic indication of a change in the condition of the unit at the substation.

Other ancillary, supervisory, and control operations are also effected by the control equipment.

2,788,515 Patented Apr. 9, 1957 The operations are accomplished by the interexchange of codes of direct current impulses at the rate of approximately l5 impulses per second, the impulses being received by each station and offered to a series of relays which are arranged in a sequence arrangement which is conventionally known in the art as a counting chain. The impulses, as received by the counting chain, are in Aturn translated into selective operations of the associated equipment at the respective stations and the desired operation of the remote units, such as circuit breakers, iS effected in an extremely competent, dependable, and reliable manner.

While the basic control and suervision of remotely disposed equipment is by far the most imortant application of the supervisory control systems, intelligent and competent control of the remotely disposed equipment requires that a complete informative picture of the condition of that equipment be available to the attendant at all times and modern control systems are accordingly equipped with so-called telemetering apparatus for effecting such functions.

The provision of such information, for reasons of economy, is desirably transmitted by the remote equipment to the attendant at the master station over the same single channel which is used for effecting the controlled operations of the remote units. it is immediately apparent that while such method is preferable from the standpoint of economy, serious problems arise in the maintaining of separate and distinct lines of division between the telemetering and operative functions, and it is to the provision of a new and novel telemetering arrangement, which solves such problems, that the present invention is directed.

According to a feature of the disclosed telemetering system of the invention, any indication which may be accontrol station, as for example, selective indications of the.

current, watts, or voltage of a chosen electrical circuit,

of the water level in a given reservoir, of the degree of opening of a flood gate, and many others.

rl`he manner in which the telemetered indications may be provided are almost as numerous as its possible applications. in one of the more conventional ararngements the equipment is arranged to provide automatic telemetered indications immediately upon selection of a circuit breaker point by the attendant, and to thereafter provide continuous telemetered indications until a reset key is operated, or until closing or trippng of the selected circuit breaker is effected. Another common arrangement is to provide telemetered indications of a selected point only as long as the atendant holds a preassigned selection key in the depressed position, the equipment automatically resetting as soon as the key is again released.

in a further application, telemetered indication may be transmitted continuously over supervisory control channel while the supervisory control equipment is at rest. The indications will be automatically interrupted when the supervisory equipment performs a control operation, and restored when the equipment returns to the normal at rest position.

in many installations Lelemetering is combined with a control function, and each control operation is followed closely by a telemetered indication of the degree of control effected to provide the attendant with a continuous picture of the status of the controlled unit. in application or" such arrangement to a iiood gate installation for instance, telemetering of the gate position may be effected as soon as the selection key is operated, and the changes of the gate position with each operation by the attendant of the raise or lower key is telemetered with each predetermined increment of change of the gate as effected. With each key operation after each movement, the telemetering will automatically be disconnected for a fracti'on of a second while the raise or lower signal is again transmitted. The operator may perform as many raise or lower operationsV asA desired, meanwhile, receiving a telemetercdy indication until the equipment is reset by the attendant. The use of combined functions in effectingl changes of feeder voltage regulators, transformer tap changers, motor operated valves, change oli-voltage, speed and. loads on generators, and opening andv closing of gates at hydro stations are only several of the applications to which such equipment may be applied.

Inv another embodiment, the equipment may also be arranged so that the device being controlled will start to move in the desired direction andwill continue in its movement until terminated by the operator, intermittent spurts of telemetering being received during the continuous movement.

While extensiveA andv variedv applications for telemetering arrangementsv have been effected heretofore, the previous incorporation of knownl types of arrangements ina supervisory control system has in many cases seriously impaired the safe operating characteristics of the supervisory system, the arrangements being such that telemetering mayv possibly effect an improper operation of a controlled unit. Other arrangementsy which have attempted to obviate such shortcomings have generally required the addition of several slow operating relay units, whichtend to further complicate the circuit operations, increase costs, and slow up the circuit operating time. Additionally, previously known telemetering arrangements have generally been such as to limit control of the remote equipment. by the attendant whenever the telemetering equipment is operative, and a tail wagging thedog condition accordingly results.

- There is, therefore, adefinite need in the art for a novel, improved type telemetering circuit which may be safely incorporated with a supervisory remote control system and in which telemetering and supervisory control may each be established over a single channel without the danger of overlapping circuit operations, and itis the object of this invention to provide such desirable type circuit. It is a specific object of the invention to provide a telemetering circuit which is quicker acting in operation, simple in arrangement, which involves a fewer number of operating units, which is more economical in construction, and which maintains a strict divisional line between its several circuit operations.

For purposes of illustration the. new and novel telemetering circuit arrangement is disciosedI inthe aforedescribedBreese; control system in which a control: station isradapted, to selectivelyv control a series of feeder circuit breaker units located at a distant station. Telemetering of the desired load characteristics of a particular one of the feeders is automatically eiected responsive to the selection of that unit by operation of the assigned selection key'. Should closing or tripping of the unit appear desirable, the attendant then operates the close or tripping key whereupon telemetering is interrupted and the equipment is reset to normal. ln the event that operationof the circuit breaker is not necessary, telemetering is continuously effected until the reset button is operated. The manner in which the novel telemetering arrangement is adapted for use in others of the previously described telemetering applications becomes immediatelyapparent from the disclosed arrangement..

Other objects and advantages ofthe invention will be understood by reference to the following speciication and accompanying drawings wherein selected embodiments of the structure are illustrated.

In the drawings:

Figures l to 12, when arranged in the manner of the figure layout set forth in Figure 13, are illustrative of the novel telemetering equipment as included in a specific installation, Figures 1 to 7 whenarranged in proper order illustrating a control oice and Figures 8 to 12 disclosing a series of circuit breaker units disposed at a remotely disposed substation; Figure 1'4 discloses in schematic form the telemetering, line supervision and signalling circuits in their basic forms; Figure l5 is illustrative of a modified arrangement whereby automatic signalling of change of position of one point is automatically elfective even though equipment is at rest on another point.

General description For purposes of illustration, the invention is disclosed in an arrangement comprising a dispatch or control office A which is adapted to automatically control equipment disposed at a distantly located substation B over a single signalling channel comprising a pair of line conductors 8S and 86. A control panel at the control station enables an attendant thereat to effect independent selective closing and tripping operations of a plurality of circuit breaker units disposed at the substation, to instantly' determine the operated condition of any one of thesel circuit breaker-units and toV receive telemetered information concerning the circuit which is controlled by the circuit breaker at the selected` point.

The circuit breaker units are of the conventional type, and in View of their similarity, only a few have been illustrated in the drawings. The circuit breaker at point twelve (l2), for-example, comprises a set of power controlling contacts (not shown), a close coil 12.90, a trip' coil 2289, and a set of auxiliary contacts 129i. Momentaryenergization of the close coil effects closing of the breaker and mechanical means-holdthe breaker in such position until suchV timeV as a momentary energization of the trip coil' orv occurrence of a line fault effects reopening thereof. Auxiliary switch contacts, such as 1291, are usedv to indicate the` breaker position to the equipment at the controlioice.

rlhe controlequipment illustrated in the present embodiment is commonly referred to as the. two-digit selection type which is operative to select any one of one hundred substation points (circuit breakers), it being understood that the features of the invention may also be embodied in the conventional one and three digit systems without departing from the scope ofthe invention.

In the two digit system, the points (circuit breakers and/or meters) areY divided into groups of ten, wherebyeach point has apreassigned group and unit number and selection of the points mayxbeaccomplished by Sequentially transmitting the group and unit identification numbers, of the desired circuit breaker.

For example, group., l of the points may comprise c ircuit breakers 1 to; 10', group. 2, may comprise circuit breakers 11 to 20, group 3 may comprise circuit breakers 21 to 3,0, etc. Thus, the circuitbreaker at point 12 is the second pointin thesecond group of points, and in selecting this point the group selection digit 2 and the point selection digit 2 are sequentially transmitted. Upon arriving at the point, automatic telemetering is eected and control of the circuit breaker thereafter may be accomplished by transmission of one; of the control codes, in`

the given embodiment, three pulses for trip and tive pulses for close In the event` that'circuit breaker operation is not required, the supervisory equipment is reset to normal by transmission of the reset code.

The installation is arranged to be controlledl in its operation by a control panel whichy is disposed at the conwhenever the circuit breaker located at the substation is in the closed position, and the green indication lamp is illuminated whenever the circuit breaker is in the open position. The white lamp associated with each of the individual control panels is operated with operation of the selection key and indicates to the operator that a particular point has been reached.

The nature of the metering equipment is determined by the type of information which is desirably provided for the attendant at the control station, and for purposes of illustration in the given embodiment, indicating meter at the control panel for point 12 is shown as being a voltmetcr instrument for indicating the voltage in the circuit controlled by the circuit breaker at substation point 12. The indicating meter at the control panel for point 1l is shown as an amineter for indicating the current flow in the circuit controlled by the circuit breaker at substation point il.

lt is to be understood that any other types of information which may be indicated at the substation may also be telemetered at the control station and are to be considered as falling within the purview or the invention.

The telemetering transmitters at the substation are conventional in nature and vary in accordance with the information to be transmitted and in view of their ac' cepted status in the art are indicated in block form in this disclosure.

The main control panel also includes a group of common control units, such as an alarm key, reset key, an alarm lamp, a trip key, a close keT a check key, an alarm bell, alarm lamp and line supervision lam-p.

Should a circuit breaker at the substation automatically change position, an alarm bell and an alarm lamp at the dispatch oiiice flash to draw the attention of the attendant thereat, the red lamp at the associated point on the control board flashing if the circuit breaker is being closed and the associated green lamp iiashing if the circuit breaker is being opened. Control keys at the panel enable the operator to silence the alarm bell, turn olf the alarm lamp, or stop the hashing or the red and green indicating lamp by operating the alarm key.

' The reset key on the control panel enables the operator to reset the equipment at the substation and the control oliice in the event of the occurrence of a stalled condition, that is a condition in which some of the relays are in the operated condition and have failed to restore the equipment to normal. The reset key is also used to restore the equipment subsequent to selection of a point for telemetering purposes.

in greater detail the initiation of a telemetering operation to procure the desired information from a given point is effected by operating the assigned point selection key at the control oilice. As the key closing operation is performed, the equipment at the control oliice is automatically eiective to condition itself for the transmission of both a set of key pulses for unlocking the substation and control ottico equipment, and a set of group identication pulses assigned to the selected point or circuit breaker.

With receipt of the first impulse, the equipment at the substation is operative to condition the equipment thereat for acceptance of the incoming coded impulses. As the key or protective impulses are transmitted from the otlice to the substation, the counting chains at each of the installations are sequentially advanced to unlock the associated equipment whereby, with receipt of the following group identification pulses, the equipment at both stations will be operated to register the group identification numeral. lt is to be noted that protective pulses are prefixed on the first digit iirst pulsing only, and that the equipment is completely conditioned tor the entire series of codes by the rst protective impulses transmitted. Following group registration, the transmitting equipment at the control oliice is automatically released and the control station is placed in the receiving condition. The

substation equipment, on completion of the registration of the group selection digit, releases its receiving members and initiates operation of the transmitting apparatus thereat to transmit a combination of impulses to the control oiice which is indicative or" the particular group actually selected, this checking operation being known as the group check operation.

The equipmment at the control oilice is operative in response to receipt of this checking code to compare the original and check-back signals, and upon agreement, doenergizc its receiving equipment, and re-energize its transmitting equipment to etect the transmission of the coded impulses which are representative of the unit identification numeral for the chosen circuit breaker.

The substation equipment is operated responsive to the receipt of the point selection digit and is eiective to registertne particular digit which has been transmitted. A check code, known as the point check digit, is thereupon transmitted back to the control oice by the substation to indicate the particular point which has been selected. As the transmission of the point check digit is completed, the telemetering path for the selected substation point is completed thereat.

The equipment at the control office accepts the incoming point check code and upon agreement elects completion of the metering path thereat and connection of the pertinent metering unit (receiver) to the line. With the metering path at the substation also completed at this point, the meter equipment on the individual control panel for the selected point informs the attendant of the load conditions at the selected point. The white lamp on the same control panel is also illuminated to indicate to the attendant that the selection is complete. In the event that operation of the circuit breaker at the selected point is not necessary, the equipment is restored to normal by operation of the reset key.

ln the event that it is necessary to trip or close the circuit breaker at the selected point, the close or the trip key is operated and the corresponding control code is transmitted to effect the desired operation of the selected unit at the substation to close or trip position. Follow ing operation of the desired circuit breaker at the substation, a close or trip indication code, as the case may be, is transmitted by the equipment thereat to the control office to indicate to the attendant that the iinal operation ot' the unit has been accomplished. The equipment at the dispatch oiiice is thereupon operative to restore its operating equipment to normal and to eifect a similar restoration of the equipment at the substation. The line supervision equipment is likewise restored to its normal condition.

Therefore, a single signalling channel comprising two trunk conductors or any medium capable of transmitting impulses is operative to eiiect, in a first key selecting operation, the transmission of a set of key or equipment unlocking pulses, a set of group selecting code irnpulses, a set of unit selecting code impulses, (these later pulses being interposed by check impulses for the group and unit selection) and to thereafter eect automatic telemetering of the characteristics of the load circuit controlled by ti e circuit breaker at the selected point; it is noted that metering of the current magnitude type may be elifected in installations which are interconnected by line conductors, and that impulse type metering is pos-A sible over installations empioying line conductors, carrier equipment or radio channel equipment as the corn-4 munication link.

The same signalling medium is also utilized by the substation apparatus to transmit signals to the control ofce to identity the automatic change of position of circuit breakers which may occur at the substation. That is, in the event of an automatic operation of a circuit breaker at the substation, the equipment thereat effects thetrans` mission of the protective pulses and group identication pulses, and upon receipt of a group check-back signal` Basic circuit description With reference now to the schematic sketch in Figure 14, th'e circuit arrangement thereshown illustrates the heart -of the new and novel telemetering arrangement as adapted for use with Tthe described remote controi system. rIhe control and controlled stations each basicaiiy comprise three separate and parallel control paths identified by the legends; metering paths Mc and Ms, line supervisory paths LSC, LSs and signalling path Sc, Ss. With 'the equipment in' its normal condition, the line supervisionipaths LSC, LSs and the signalling paths Sc, -Ss are parallelly -connected at each of the stations in series with the line circuit conductors 85 and 86 and the line relays 630 a-nd 1000. The metering paths Mc and Ms at each of the stations are normally disconnected from the line circuit and are arranged to be prepared for series conn'ection with the line conductors and parallel connection with the signalling paths Sc and Ss simultaneous with disconnection of the line supervision paths LSC and LSs.

The alternative line supervision and metering path connections are performed at the control station by contacts 32551 and 32511 and at the substation by contacts 872 and 873. Completion of the prepared metering paths is effected following the completion of the point selection operation, such operation being more clearly brought out by the subsequent disclosure. Metering is thereafter continued until the reset key is operated.

'Considering briefly the close interconnections of the line supervision, metering and signalling circuits, reference Ais again made to the sketch in Figure 14. As there shown, the signalling and line supervision paths will be normally completed and substation battery potential is supplied thereto over a circuit extending from positive battery over resistance H3, contacts 1011, line relay 1000, contacts 10Std, conductor 85, contacts 666, line relay 680, line supervision relay 605, conductor 31, contacts 3251), conductor 30, resistance 659, contacts 669, conductor $6, contacts 1912, conductor 1361, contacts 8855, `"contacts 873, resistance S72 to negative battery.

The circuit characteristics are calculated so as to normally supply energizing current of approximately 2 milliamperes overv the signalling channel. Line relays 630 and 1000 are low resistance relays which operate on approximately 6 milliamperes, whereas the line supervision relay 685 is a high resistance relay which operates at approximately ll/z milliamperes. It will be apparent, therefore, that the line relays 680 and 1060 will be normally restored and the line supervision relay 685 will be normally operated. It should be notedthat rectifier- 66dblocks current iioW in the signalling path while the equipment is in the normal standby condition Assuming now the operation of the control station equipment to select a point for metering or operating purposes', impulse sending relay 665 at the `control station is 'operated to 'tran'sr'nit signals over both signalling paths Sc and Ss, "the local path extending 'from positive battery at the control otiice over resistance 65S, contacts 668, path Sc, rectifier 664, line relay 680, resistance 674, ycontacts 667 and resistance 657 to negative battery, and the second path extending from positive battery over resistance 65S, contacts 668, C86,`path Ss, rectiiierr1006, line relay 1000, contacts 1614, C85, conta'cts '667 and resistance 657 to negative battery. The parallel connection of the line relays in the signalling 8 arrangement, of course, effects a more positive acting relay arrangement. Y V

With the initiation of signal transmission, outgoing start relay 322 at the control station 'is operated and is eifective at its contacts 325e and b to control vthe disconnection of the line supervisory circuit LSC from the line circuit conductors and 86, and to prepare the metering path Mc for parallel connection with the signalling pathSc.

A similar circuit transfer is effected at the substation by the incoming start relay 870 at its contacts 872 and 873. The metering paths are opened at several points for the period that the signals are operative to select the desired point and the operation of the meter vby the transmitter signals is prevented. Further, with operation of the impulse relay contacts 668, the metering path is parallelly connected with the signal path only during the interval that the open circuit condition exists in 'the signalling path. The danger of intermixing of telemetering and control signals is accordingly completely eliminated.

The metering paths are connected in `parallel with vthe signalling paths to effect the metering operation only after selection of the desired point is effected. Assuming, for instance, the selection'of point 12 at the substation, the energizing path for the meter .associated with that point will extend from positive battery at the transmitter over resistance 1018, contacts 1011, line relay 1000, contacts 1014, C85, contacts 666, relay 680, C42, nieter 119, contacts 195, C47 `contacts 373, 352, 325e, C30, resistance 659, contacts 669, C86, contacts 1012, C1361, contacts S88, 372, 836, 811, C1343 and contacts 1218 to the negative battery at the transmitter. The telemetering current alone is insuflicient to operate the line relays, and since the control station cannot connect potential to the line without disconnecting the metering circuit, the danger of false operation of the equipment during telemetering is eliminated. Reset of the equipment is effected by operation of the reset button whereupon the signalling and line supervision ,paths are parallelly reconnected in series with the line circuit.

Since the signalling paths Sc and Ss are connected `to the -line conductors 85 and 36 even during metering of a selected point, immediate signalling by the substation of a circuit breaker operation, which occurs after the close control code has been transmitted by the control station, can take place at any time without having to transfer the equipment lfrom the metering to the signalling paths. For example, should an automatic trip loccur vat the substation during the period described, impulse sending relay 1010 is operated to ltransmit an indication of the trip which occurred. Since the signalling paths are connected for operation at all times, the signals are transmitted as soon as the sending equipment is energized and the metering path is immediately interrupted by contacts 1012. The signalling circuit thus assumes control in the desired manner, even though telemeterin'g is being accomplished. The signalling paths `for substa-- tion reporting extends locally from positive battery over resistance 1013', contacts 1013, rectifier 1006, line `relay 1000, resistance 1007, contacts 1015 and resistance 1015 to negative battery. The second path extends from positive battery over resistance 1013', contacts 1013, conductor 86, rectiiier 664, line relay 630 contacts 666, conductor 3S, contacts 1015 .and resistance 1015 to negative battery.

The foregoing paths have been traced to bring out more clearly the direction of current flow in the various paths and the advantages which accrue therefrom. First, it is noted that the battery potential sources for the metering circuit and the line supervision circuit are con' nected `so that the metering and 4line supervision currents traverse through their respective paths and the line circuit conductors 85 and 86 in the same direction; it bei ing remembered, however, that at'no time are these two circuits simultaneously connected to the line circuit. Secondly, with reference to the directional arrows at the substation, it is seen that the signalling current is arranged to travel over the signalling path in the same direction as the currents which traverse the line supervision and metering paths thereat. On the other hand, the signalling path at the control station is arranged to conduct current in a direction opposite to that in which the currents in the line supervision and metering paths .are conducted. An outstanding advantage of such arrangement is the ability to connect the line supervision, signalling, and metering circuits in parallel and still maintain a distinct division line between the energizing circuits for these circuits.

Also, with the parallel paths at the substation conduce ing in the same direction in the event that signalling is initiated by the control office during line supervision or metering, the currents of the several circuits will be additive and a stronger operative signal is provided. Specicially, a line relay pre-energizing effect is obtained whenever a signalling operation is effected following a metering operation or line supervision; the metering and supervisory currents in their flow through the line relays tending to effect partial energizatiou of the line relay windings.

A further advantage inherent in the parallel connections is the elimination of the need for superimposing Description of apparatus The arrangement as shown for purpose of illustration comprises a control oiice A and a substation B which are interconnected by a single signal channel comprising a pair of ,line conductors 35 and 86. Control oice A includes a control panel which has been previously described herein, frorn which the attendant may control the operation of the automatic transmitting and receiv-' ing 'equipment at the control ofce and at the substation.' T he illustration of the individual points at the controllingl olice and substation has been restricted to the showing of several points such as points 11, 12, 21 and 22 in. the

interests of a clear and concise disclosure.

The transmitting and receiving equipment which is disposed at the substation and the control office are sorn'ewhat alike, and by reason of the large number of individual elements in each station the general disclosure of this equipment, together with their function, may be -best set forth by means of the chart shown below:

Relay functions Control Substation,

Location, Figs. 7-12 Function Figs. 1-6 Relay Relay 680 1000 Line Relay-Connected to the line wires 85 and 86 in parallel, being normally released. Operates when the line is energized for pulsing at either end.

384 835 Receiving Relay-Operates at the start of an incoming code. Since it is a slow-release relay, it does not release between impulses but releases only ait-er a code of impulses has been completed.

370, 380 825, 830 Receiving Control Relays-Energize after the first impulse is completed in an incoming code. After selection has been made and locked up they release to terminate the receiving condition.

665 1010 Impulse Sending Relay-Operates to send impulses by energizing the line.

360 820 Sending Control Relay-Controls the operation of the Impulse Sending Relay. v

340, 350 810, 815 Sending Drive Relays--Energize at the start of au outgoing code. After the code is completed they release to terminate the sending condition and release the counting chain.

336 Lockout and Reset Relay-Operates to cause reset of equipment ii dispatcher-s otlce and substation start sending simultaneously, and equipment attempts to send or receive more impulses than can be registered on the counting chain, or ifa non-registering or transient code is received.

80.5 Lockout Relay-Operates to cause temporary lockout of the substation if two or more stations start sending simultaneously or if a non-registering group code is received. If two or more stations start sending simultaneously the station sending the highest group selection code causes all other stations to lockout until reset by the dispatchers oce. Also causes lockout-of station if equipment attempts to send or receive more impulses than can be registered on the counting chain.

525 Alarm Relay-Operates the alarm and the alarm lamp.

....... 800, S60 Time Delay Relay-Operates in cascade during a reset Voperation to delay the sending relays at the Remote Location and allow the Control Location to eut in and perform an operation. These relays are of the extra-slow release type.

670 1090 Group Stop Relay-Stops the impulsing when the correct number oi impulses has been sent in the group selection code.

660 1080 Group Code Relay-Locks up the selected group.

650 1070 Group Cheek Relay-Stops the impulsiug when the correct number of impulses has been sent in the group check code.

640 1060 Point Stop Relay-Stops the impulsing when the correct number' of impulses has been sent in the point selection code.

630 1050 Point Code Relay-Locks up the selected point.

624 1040 Point Check Relay-Stops the impulsing when the correct number of impulses has been sent in the point check code.

605 Y Battery Supervision Relay-Normally held energized and releases only when the eoutrol power is shut olf, operates the reset relay when power is turned ou again.

322, 326 875, 880 Start Relays-Operate at the originating end to mark that end as the original starting end.

315 8 Start Relay-0perates at the end conditioned in the receiving state for the present transmission.

310 865 Cheek Bach Relay-Operates to reset the equipment; when, in response to a `previously transmitted selection code, a diereut check code is received.

550,560 1130-1140 Group Selection Control Relays-Operate on termination of an incoming group selection code to connect the counting cha-in contacts to the coils 'of the group selection relays.

530, 540 1110-1120 Point Selection Control Relay-Operates on termination of an incoming point selection t code to connect the counting chain contacts to the coils of the point selection relays.

280 Supervision Control Relay-Operates on termination oi au incoming' supervision codo to connect the counting chain contacts to the coils of the indication control relays.

Chain 5315-960 Impulse Counting Chain Relays-Chain relays operate on successive operations of the Relays line relays to count the impulses. Sequence relays operate in succession as the line 215-260 relays are de-cnergized after each impulse to canse the counting relays to operate in sequence.

500 Check Relay-Operate when cheek key is operated to cause equipment to send check .v code of one impulse. 505 1100-1105 Master Check Relay-Relay 1105 operates in response to master check codo to causevv release of'all H relays. Relay 1100 at the substation and rela-y 505 at the dispatcher's Y,

oihce serve as point selection relays on master check. Y'

610, 610. OperatlonfCode Control Relays-Operate to cause equipment to send operation controlf codes. Relay 620 alone sends trip code-3 imp. Relays 510 and 620 together send Vclose f essere Asubstation,

Figs. F12 Relay Function godeinp. Relay 610 stops the impulsing when the correct number of impulses has een sen Supervision Code Control Relaysr-Relay 1030 starts transmission of supervision code.

Relay 1020 stopsthe impnlsing when the correct number. of impulsesvhave been sent.

Vision code has been recorded. I I Indication Control Relay-Controls the number of impulsesto be sentin the supervision code. Released sends three impulses, operated ve impulses.

vision is received to hold the point selection for further operations and prevents recycling of equipment until control key is released.

impulses` Reset Relay-Operates under control ol line relay to energize the auxiliary positive bus and releases to drop all relays being held by this bus. a I ,I l v v Aux. Supervision Control-Operates upon receipt oi a supervision code in`disagreement with the position ofthe point indication relay` position and operates alarm relay 525.

of the control MS relays in order to insure complete operation of controlled devic Preliminary Protective Pulse Termination Relays-Operate at the end of the'p inary protective pulses and transfer countingichain to normal counting sequence ion. x h, Line Supervision Relays-Relay 685 (high resistance) is held opeated'in-serie visi'ng the line. Releases upon an open-line condition or upon a minimum leakage. Relays 690 and 695 controlalarms. Relay 698 operatcsir'om thealarm key and cuts ofi the audible alarm. a

Guard Relays-Operate after the point selection key is operated, to guard against the possibility of more than one point, code being set up. Relay 791 is point guard and relay 794 is group guard.

cause indication lamp to flash on associated escutcheo'n.A Y Point Start Relay-Operate when selection keys are operated to cause the'properpoint Indication Agreement Relay-Operates to initiate reset oijequipmcn't 'after the super- Anti-Recycling Key-Operates when master control ley'is heldv operated until after super- Reset Control-initiates and terminates the long vresetV impulse. 4Relaysffil) and 845 Y' operate in conjunction with 850 and 855 to reset substation upon receipt of transient i Causes point indication relay to change l Time Delay Relays-Operate alter a control operation to prevent the immediate'l'r'elese 1.1mposiline relays which are non-operated, from current supplied at the substation, sup'cr- I Flashing Alarm Relays-Operate when an automatic cha-nge of indication is recorded to 70o, reo

selection code to be sent.

vidual control and indication circuits,

switch to indicate position of the device.

indication lamp to ilash.

patcher-s oliice. 1292 telemcterirufI transmitter.

Group Start Relays-Operate when selection keys are operated or when H relays drop to cause the proper group selection code to be sent.

Group Selection Relays-Operate in response togroup selection code-to prepare-theoperating circuits for the ten associated point selection relays. M

Point Selection Relays-Operate in response to the point sclection'codeto close the indi- Point Indication Relays-Operate and release under control of the y*breaker auxiliary Point Flashing Alarm Relay-Operates on an automatic change of indication to cause Automatic Point Start Relay-Normally energized and releases each time the associated device changes position to cause the change oi'indieation to be transmittedto the dis- Metering Relay-Operates upon arrival at a metering point to connect metering source to Explanation of codes All operations 'are performed by alternate transmission of codes between the control station vequipment and the substation, th'e sequence of the codes when an operation is performed by the operator at the control station being a's follows:

Remote Location Control Location Transmits Transmits Group Selection Code...

Group Cheek Code.

I Point check Code.

Supervision Gode.

Reset Ccd When the remote location reports as operation to the control location, the codes are transmitted as follows:

Remote Location Transmits' l Control Location t Transmits Group Selection Code.

Point Selection Code.

Supervision Gode.

Group Check Code Remote control Selection and operation A more thorough understanding of the apparatus of the invention will now be had ,with reference to the drawings and the following detailed description of the functions of the equipment shown thcreat, responsive to the operation of a selection key on the control board at the control station. A ground symbol is used in the diagrams to indicate positive battery. Also it is noted that the s't digit of the identification numbers for the various elements are indicative of the figure in which the element appears. q

With the control office and substation equipment in their normal restored conditions, positive and negative battery are applied by the substation to the signalling channel over a circuit extending from positive battery over resistance 1018, contacts 1011, the winding of line relay 1000, contacts 1014, C85, contacts 666, the Winding of linc'r'elay 680, the winding of line supervisory relay 685, C31, contacts 325b, C30, resistor 659, contacts 669, C86, contacts 1012, C1361, contacts S88, contacts 873, resistance 872 to negative battery. The circuit charactcristcs are calculated so as to normally supply energizing current f approximately 2 milliamperes over the signalling channel'. Line relays 680 and 1000 are low resistance relays which operate on approximately 6 milli- Y ar'nperes, whereas the line supervision relay 685 is a high resistance relay which operates at approximately 11/2 millia'mperes. It willv be apparent, therefore, that the line supervision path and signalling paths are normally connected in parallel and that the line relays 630 and 1000 will be normally restored and the line supervision relay f .685 will be normally operated. Line supervision relay 685 Vat its contacts 686 completes an obvious operating crcuitffass'ociated relay 695 and this relay is, therefore, also normally operated. 

